Question

How does the radius affect the moment of inertia?

Answer 1

Moment of inertia is directly proportional to the square of the radius.

Explanation:

The moment of inertia, `I`, of a single mass, `M`, being twirled by a thread of length, `R`, is
`I = M*R^2`

A body that is being rotated will closely resemble that relationship. The formulas for various geometric shapes are derived with integration. For example, for a solid sphere, moment of inertia is
`I = (2/5)*M*R^2`

I hope this helps,
Steve